Information traffic on the Internet is
doubled every year. Although the present optical communication system is the key
technology that supports the expanding Internet, we need higher transmission
speed, larger transmission capacity, and more flexible signal processing
capability in the future optical communication system. The technology
innovation is now strongly expected to meet these requirements, because it
becomes more and more difficult to cope with the bursting traffic simply by
improving current technologies. In our laboratory, aiming at such technology
innovation, we have been investigating the optical fiber network from various
points of view such as physics, information theory, optical devices,
measurement, and network architectures.